Experimental Investigation of the Condensed Combustion Products of Micro Aluminized Solid Rocket Propellants

Main objective of this experimental work is to understand how details of aluminized propellant formulation s affect the condensed combustion products (CCPs) formation and growth. Connections among propellant steady burning rate, morphology, and composition on one hand vs. agglomerate amount and quality on the other hand were investigated for four industrial multimodal propellant formulations. A high-speed and high-resolution video recording system was used to visualize the aggregation/agglomeration birth at/near the burning surface and their evolution in the gas phase. The combined results from a variety of diagnostic techniques confirm that steady burning rate and pressure sensithity increase depending on fine AP amount and size, while larger fractions of coarse AP grains depress steady burning rate and pressure sensitivity. Condensed combustion products were analyzed with advanced techniques (Scanning Electron Microscopy, X-Ray Photoelectron Spectroscopy and X-Ray Diffraction) to determine morphology, chemical composition and crystalline structure. Increasing the fine AP mass fraction, decreasing the coarse AP size, and increasing steady burning rate all lead to decreasing agglomerate average size. Any even minute change in propellant composition or test conditions, resulting in a burning rate increase, indicate a decrease in the agglomeration level.